JPH04225855A - Coating material replenishing device in electrostatic powder coating apparatus - Google Patents

Abstract

PURPOSE:To keep the ejecting quantity of the powdery coating material constant by providing a screw feeder at a lower part of the hopper and introducing the powdery coating material being fed at a constant quantity to the intake port of the injector. CONSTITUTION:The powdery coating material is sent out from a discharge port 10 with the screw feeder at the lower part. Namely, as the screw 9 rotates with a motor 12, the powdery coating material at the lower part in the hopper 5 is pushed out to the discharge port 10. With this pushing force, a spring 19 is shrunk and the can plate 17 is opened and from the slit between the cap plate 17 and the discharge port 10, the powder coating material is blown out. Later, the powdery coating material blown out from the cap plate 17 and the discharge port 10 strikes the inner face of a flow straighting part 13, and while travelling on the inner face of the flow straighting part 13, the powdery coating material is fed at a constant quantity to the intake port 29 of the injector 28 through a chute 26 from a falling port 14.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention utilizes an injector to supply powder paint from a paint tank to a paint gun.
The present invention relates to a paint supply device in an electrostatic powder coating device.

0002

[Prior Art] Conventionally, this type of paint supply device has a structure in which an injector is directly installed on the side or top of a paint tank containing powder paint, and a paint gun is connected to this injector via a hose. The powder paint in the paint tank is sucked together with air by an injector, and the air is used to transport and supply the powder paint to the paint gun.

0003

[Problem to be Solved by the Invention] By the way, the amount of paint discharged from the paint gun in the paint supply device as described above is determined by the air pressure and amount of air of the injector, and it is necessary to obtain a coated surface with a uniform film thickness. For this purpose, the amount of paint dispensed from the paint gun must be constant.

However, even if the air pressure and air amount of the injector are not changed, when the amount of powder paint in the paint tank decreases, the air content in the powder paint increases and the layer of powder paint Since the pressure changes depending on the thickness, the amount of powder paint sucked in by the injector decreases,
The amount of powder paint dispensed from the paint gun is reduced. For this reason, the thickness of the coating film was not uniform, which sometimes caused scratches on the coated product and defective products.

[0005] Furthermore, if the powder paint is stuck or foreign matter is clogged in the hose between the injector and the painting gun, a pressure loss will occur in the hose, which will reduce the amount of paint sucked by the injector. The amount of powder paint discharged from the paint gun changes.

[0006] Therefore, in the conventional paint supply device in which an injector is attached to the paint tank and the powder paint in the paint tank is directly sucked, it is difficult to maintain a constant amount of powder paint discharged from the paint gun. was difficult.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a paint supply device for an electrostatic powder coating apparatus that can maintain a constant amount of powder paint discharged from a coating gun.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the technical means taken by the present invention are to
A discharge means is provided to discharge the powder paint in the paint tank, a hopper is provided to receive the powder paint discharged from the discharge means, a screw feeder is provided below the hopper, and the powder is supplied in a fixed amount from the screw feeder. The body paint is introduced into the injector's suction port.

[0009]

[Operation] According to the above means, since a fixed amount of powder paint is introduced from the screw feeder into the suction port of the injector, there is no need to draw out the powder paint in the paint tank by the injector. Therefore, even if the amount of air in the injector changes, a constant amount of powder paint is discharged from the coating gun.

0010

[Embodiment] An embodiment of the paint supply device according to the present invention will be described below.

The paint tank 1 is of a fluid type. In order to improve the dispersibility of the powder paint, the fluidized paint tank 1 uniformly blows air into the powder layer through a perforated plate 2 provided at the bottom to fluidize the powder paint.

A discharge pipe 4 equipped with a pinch valve 3 is connected to the lower part of the paint tank 1 as a means for discharging the powder paint, and by opening the pinch valve 3, the powder in the paint tank 1 is discharged. The paint is discharged by falling downward.

The lower end of the discharge pipe 4 is connected to the upper part of the hopper 5. The hopper 5 is provided with a level switch 6 that detects the amount of accumulated powder paint supplied into the hopper 5. A lid 7 is provided on the upper surface of the hopper 5, and the lid 7 is provided with an air vent. As a result, excess air present between the powder coating materials charged into the hopper 5 is removed, and the amount of powder coating material per unit volume of the powder coating material in the hopper 5 becomes constant.

A screw feeder 8 for feeding powder is installed at the bottom of the hopper 5. The tip of the screw 9 of this screw feeder 8 faces a discharge port 10 provided on the bottom side of the hopper 5. The rear end of the shaft of the screw 9 is drawn out of the hopper 5 and connected to a motor 12 via a joint 11. A cylindrical rectifying section 13 having a drop port 14 below is provided on the side of the discharge port 10, and a spring housing chamber 15 is provided on the side of the rectifying section 13. A support shaft 16 is provided at the tip of the shaft of the screw 9 so as to pass through the rectifying section 13 and the spring housing chamber 15.
are connected. A cover plate 17 that closes the end face of the discharge port 10 is movably fitted onto the support shaft 16 in the rectifying section 13 . A pipe 18 whose tip is drawn into the spring storage chamber 15 is placed over the support shaft 16 on the back side of the cover plate 17.
is fixed on the back of the A spring 19 is fitted into the support shaft 16 in the spring storage chamber 15, and the spring 19 presses the cover plate 17 against the discharge port 10 via the pipe 18. At the tip of the support shaft 16, a receiving plate 20 for receiving the tip of the spring 19 is provided so as to be movable with respect to the supporting shaft 16. By moving this receiving plate 20, the strength of the spring 19 can be adjusted. can. An air introduction pipe 21 is connected to the spring housing chamber 15, and the inside thereof is maintained at a positive pressure state. This prevents powder paint from flowing into the spring housing chamber 15. A stirring rotary wheel 22 is rotatably supported in the lower part of the hopper 5. Protrusions 23 that enter the pitch gap of the screw 9 are provided on the circumferential surface of the stirring rotating ring 22 at predetermined intervals, so that the stirring rotating ring 22 rotates in conjunction with the rotation of the screw 9. There is. Further, a damper plate 24 is installed inside the drop port 14 of the rectifying section 13, and by changing the angle of this damper plate 24, the drop port 14 can be adjusted.
4 can be varied in size, so that when dispensing a small amount of powder coating, the powder coating does not spread out and scatter. Further, the screw feeder 8 is configured to be detachable from the hopper 5, and the screw 9 of the screw feeder 8 is configured to be detachable from the hopper 5.
The casing 25 is also replaceable.

Below the drop port 14 of the rectifying section 13,
A chute 26 is installed, and an exit 27 of this chute 26
A suction port 29 of an injector 28 is connected to the injector 28 . A hose 31 is connected to the discharge port 30 of the injector 28, and a coating gun 32 is connected to the tip of the hose 31. A sensor 33 is installed in the chute 26 to detect when powder paint is deposited near the outlet 27. Further, the amount of air supplied to the injector 28 may be sufficient as long as it is enough to discharge the powder paint supplied from the screw feeder 8 in a fixed amount to the suction port 29 of the injector 28 from the paint gun 32 through the hose 31. By installing an electropneumatic regulator in the air circuit, it is possible to supply the minimum amount of air according to the discharge amount by electrical control.

Further, a sieve may be installed at the drop port 14 of the screw feeder 8 in order to improve the dispersibility of the powder coating material. Further, in FIG. 1, reference numeral 34 indicates a height-adjustable base.

In the paint supply device constructed as described above, first, the pinch valve 3 is opened and closed at predetermined intervals to supply a predetermined amount of powder paint to the hopper 5. It is designed to accumulate, and the amount of accumulation is detected by a level switch 6. Therefore, by electrically monitoring the opening/closing of the pinch valve 3 and the time taken to reach the level switch 6, it is possible to detect an abnormality in the powder supply amount. That is, if a blockage occurs somewhere in the powder supply line, the powder paint in the hopper 5 will not be consumed, so the pinch valve 3 opens and the time required for the powder paint to reach the level switch 6 is monitored. shorter than the cycle time. Also, from paint tank 1 to hopper 5
If the powder supply line to is abnormal, the pinch valve 3 opens and the time it takes for the powder paint to reach the level switch 6 becomes longer than the monitoring cycle time. As described above, if the time falls outside the monitoring cycle time, it is regarded as an abnormality and the line is stopped.

Next, excess air naturally escapes from the powder coating material supplied into the hopper 5 during deposition. and,
The powder coating material in the hopper 5 is fed out in fixed quantities from a discharge port 10 by a lower screw feeder 8. That is, when the screw 9 is rotated by the motor 12,
The powder coating material in the lower layer in the hopper 5 is pushed out toward the discharge port 10. This pushing force causes the spring 19 to
is contracted, the cover plate 17 is opened, and powder paint is blown out from the gap between the cover plate 17 and the discharge port 10. Thereafter, the powder paint blown out from the cover plate 17 and the discharge port 10 hits the inner surface of the flow straightening section 13 and moves on the inner circumferential surface of the flow straightening section 13, while moving through the fall port 1.
4, a fixed amount is supplied to the suction port 29 of the injector 28 via the chute 26.

Thereafter, the powder paint supplied to the injector 28 passes through a hopper 31 by air and is discharged from a coating gun 32.

Next, when the powder paint becomes clogged in the hopper 31 or the like, the powder paint overflows from the suction port 29 of the injector 28 and accumulates at the outlet 29 of the chute 26. This accumulation of powder paint at the outlet 27 of the chute 26 is detected by the sensor 33, so if the coating line is stopped based on this, it becomes possible to minimize the occurrence of defective products.

[0021]

Effects of the Invention As described above, according to the present invention, powder paint is supplied in a fixed quantity to the injector, so even if a small pressure loss occurs in the hose of the paint gun, the powder paint is not discharged from the paint gun. The discharge amount can be kept constant.

[0022] Furthermore, by changing the rotational speed of the screw of the screw feeder, the amount of powder coating introduced into the injector can be easily changed, so the amount discharged from the coating gun can be arbitrarily selected. is possible.

[Brief explanation of the drawing]

[Figure 1] Overall configuration diagram of the embodiment

[Figure 2] Cross-sectional view of the hopper and screw feeder part

[Explanation of symbols]

1 Paint tank 2 Pinch valve 5 Hopper 8 Screw feeder 9 Screw 10　Discharge port 13 Rectifier section 15 Spring accommodation chamber 17 Lid plate 19 Spring 26 Shoot 28 Injector 31 Hose 32 Paint gun

Claims (3)

[Claims] Claim 1: In a paint supply device for an electrostatic powder coating apparatus, in which a paint tank containing powder paint and a paint gun are connected via an injector and a hose, the powder in the paint tank is supplied to the paint tank. A discharge means for discharging the paint is provided, a hopper is provided to receive the powder paint discharged from the discharge means, a screw feeder is provided below the hopper, and the powder paint supplied in a constant quantity from the screw feeder is sucked into the injector. A paint supply device for an electrostatic powder coating device, characterized in that the paint is introduced into the mouth. 2. The screw feeder according to claim 1, comprising: a casing having a discharge port formed at a lower side; and a screw having a tip facing the discharge port; A cylindrical flow straightening section having a falling port is provided, a lid plate for closing the discharge port is provided movably in the axial direction of the screw, and biasing means is provided for pressing the lid plate against the discharge port. A paint supply device for an electrostatic powder coating device, characterized in that: 3. A paint supply device for an electrostatic powder coating apparatus, wherein the biasing means according to claim 2 is a spring, and the spring is housed in a housing chamber maintained under positive pressure.